Get weekly leaderboard

Example response

{
  "period": "last_7_days",
  "start_date": "2024-03-13",
  "date_range": "Mar 13 - Mar 20, 2024",
  "generated_at": "2024-03-20T10:00:00Z",
  "entries": [
    {
      "rank": 1,
      "user": {
        "id": 42,
        "username": "goat_heidi",
        "avatar_url": "https://..."
      },
      "total_seconds": 14500.5
    }
  ]
}